Commercial hot lather dispensers have been available for many years and are most commonly found in barber shops. There, the consistency of the lather or other foaming liquid is known so the dispenser can be designed accordingly. Furthermore the size of the foaming liquid container, if any is used, is set, allowing for a appropriate sizing of the dispenser. Additionally the sales price can be rather high since it is for commercial purposes and must work reliably over many years of heavy usage.
In contrast, when designing a foaming liquid dispenser for the consumer market, the designer must allow for a wide variety of formulations of foaming liquid, must build the dispenser inexpensively so that its price will appeal to the consumer, and must allow for different size containers of foaming liquid.
First, with reference to the variety of foaming liquids on the market, it has been found that the dispenser heater, in order to heat an initial charge of some formulations of foaming liquid, that an overheating occurred to the point of producing steam and/or very runny liquid. The "initial charge" is the volume of foaming liquid that passes through the heating compartment when the user initiates discharge from a supply of foaming liquid.
Second, because of cost constraints, it is not economically feasible to have means for adjusting the heating temperature to accommodate the various brands of foaming liquid.
Third, home size shaving cream containers of various brands presently come in plural differing volumetric sizes which must be handled by the foaming liquid dispensing apparatus. The diameter of each size is often the same but there is difference in the length dimension of the containers. Obviously the sizes of container can vary at the whim of the respective brands' marketing staff.